Field of the Invention
The present invention is related to a cutter knife, which can be surely prevented from being entered into other products as a foreign substance.
Description of the Related Art
For example, regarding products of mattress or stuffed toy animal, sometimes a cutter knife used during manufacturing process may remain in the products as a foreign substance. The cutter knife as the foreign substance is to be found by a metal detector and taken out.
For surely being found by a metal detector, the cutter knife may preferably include many metal components. Theoretically, even a common cutter knife, the body of which is made of plastics, could be found by a metal detector, because the blade of which is made of metal. But actually, a cutter knife having less metal components could pass by the metal detector, without being found.
In order to optimally be found by the metal detector, the whole of a cutter knife including its body would be all made with metal parts. The cutter knife made with only metal parts has been already put on the market by the applicant, and was also published in a Japanese magazine of Weekly MAINICHI-GRAPH of Oct. 7, 1979.
However, if the whole of a cutter knife is made with metal parts only, there may be a problem, that is, smoothness of sliding operation of the cutter knife blade could be degraded in time because of friction and the like, particularly in a type of a cutter knife wherein its blade is extended and retracted in a sliding manner. In order to prevent this, lubricating oil or friction resistant coating may be applied, but it could bring another problem, below.
That is, because of the lubricating oil, products of mattress or stuffed toy animal could get dirty, or otherwise, there may be a sanitary problem when the cutter knife is used in the field of foods. Further, applying the friction resistant coating could increase the manufacturing cost.